Multiple layer stay tape



sept. s, '1953 D. s. BRUCE ET AL 2,651,588

MULTIPLE LAYER STAY TAPE Eiled Aug. l5, 1950 ATTORNEYS.

to iiex independently of each other.

Patented Sept. 8, 1953 MULTIPLE y LAYER STAY TAPE Donald S. Bruce, PaulW. Herrlinger, and Howard L. Heise, Troy, Ohio, assignors to The GummedProducts Company, Troy, Ohio, a corporation of Ohio Application August15, 1950, Serial No. 179,622

- cally, our invention has to do with the provision of a multiple layerstay tape in which the individual layers of the tape are free of eachother in the area which will bridge an angular edge of the carton towhich the tape is applied.

In the manufacture of boxboard cartons, particularly shipping cartonsmade of corrugated board, it is customary to form the carton body bytubing a blank having four body walls in articulation. Cartons Iof thischaracter are not provided with an attachment flap for tubing the bodyWalls; but rather the body Walls are tubed simply by bringing their freeedges adjacent each other and applying over the adjacent edges a stripof stay'tape, the tape being adhered to contiguous marginal portions ofthe adjoining wall panels. The tape may be applied when the tubular bodyis in nat condition, the walls being joined lying substantially coplanarwith respect to each other and shipped to the user in knockeddowncondition. However, there are instances wherein the tape is applied tothe carton when it is in substantially set up condition, in'which casethe tape is folded longitudinally about the edge of the structure beingsealed. Following erection of the carton, including the closure of itsbottom, the contents are placed in the carton 'followed by the closingand sealing of the top closure. j

It has been found that the contents of a carton will exert outwardlydirected forces against the walls of the carton which, while they maynot be sufficient to burst the Walls of the carton, Will at times besufficient to split or burst the tape securing the edges of the wallpanels to each other. This is particularly true in larger lcartonshaving substantial volume; and even Where the 'tape is reinforced, suchas tape reininforced with spaced laterally extending threads, there isstill a marked tendency to split or burst along the seam. y

It is a principal object of our invention to provide a stay tape whichis made up of a plurality of relatively thin layers of tape formingmaterial and capable of withstanding the forces eX- erted againsttheedges of a carton to which it is applied.

It is an object of our invention to provide a multiple layer stay tapein which the layers are adhered to each other only along marginal edges,

the intermediate areas of the layers being free We thus take advantageof the superiority in shock resistance and ultimate strength of amultiplicity of relatively thin, relatively free moving members ascompared to an equal bulk of the same basic material in essentiallyunitary form.

It is a further object of our invention to provide a continuous processfor the manufacture of multiple layer stay tape wherein a plurality oftape widths may be fabricated as a unit and thereafter severed intosingle tape width.

These and other objects of our invention which will appear hereafter orwhich will be apparent to one skilled in the art upon reading thesespeciiications, We accomplish by those constructions and arrangements ofparts of which we shall now describe certain exemplary embodiments.Reference is now made to the accompanying drawings` wherein:

Figure 1 is a diagrammatic side elevation of Y means for applying spacedlongitudinal stripes of adhesive to a sheet of tape'forming material.

Figure 2 is a sectional view taken along the line 2 2 of Figure 1 andshowing a cross sectional portion of the gummed web.

Figure 3 is a partial perspective of the wiper blade employed with theglue applying roller of Figure 1.

Figure 4 is a diagrammatic side elevation of a device suitable forforming multiple layer stay tape in accordance with my invention.

Figure 5 is an exploded viewtaken along the line 5-5 of Figure 4 andshowing the three webs of tape forming material prior to theirassociation with each other.

`Figure 6 is similar to Figure 5 but illustrates the webs after theyhave been pressed together.

Figure 7 is a partial perspective View With parts stripped away showinga single width of tape.

Figure 8 is a cross sectional view of the strip of multiple layer tapeillustrated in Figure '7.

Figure 9 is a partial perspective View of the tape applied to a boxboardcarton.

Figure 10 is a sectional view taken along the line l0-Hl of Figure 9 andillustrating in somewhat exaggerated fashion the action which occurslwhen the multiple layer tape is folded about an edge of a carton.

Figure 11 is a cross sectional view of an alternative form of multiplelayer tape.

Figure 12 is similar to Figure 11 excepting the tape is in completedcondition with its free ends adhesively secured to adjacent portions iofthe tape.

Referring now to Figure l of the drawings,

the reference numeral I indicates a supply roll of suitable tape formingmaterial, which may be kraft paper, fabric or the like. A continuous web2 of the tape forming material is Withdrawn from the supply roll I andpassed over glue applying means 3 where spaced longitudinal stripes ofadhesive are applied to the web.v

The glue applying means comprises a glue pot 4, transfer roll 5, wiperblade 6 and applicator roll l. As will be explained more fullyhereinafter, the adhesive applied to the web is preferably athermoplastic adhesive and hence the glue pot 4 is provided with heatingmeans 8.

The glue applying means is of a length equal at least to the width ofthe web being acted upon and the spaced stripes of adhesive are obtainedby means of the wiper blade 6 which is indented in the mannerillustrated in Figure 3,'having scraping portions 9 and indentedportions Ill. The scraping portions 9 will be in contact with the glueapplicator roll 'I and hence will scrape the adhesive from the roll inthe areas which they contact, thus leaving stripes of adhesive only inthe paths of the indented areas I0. The stripes of adhesive so formedwill be transferred to the web 2 by the roller 1, as will be readilyunderstood. The width of the glue stripes and their distance apart willbe determined by the size of the individual tape widths being produced.

After passing the glue applying means, the web 2 is passed around acooling or drying drum Il which will solidify the stripes ofthermoplastic adhesive applied to the web. The web is, of course, passedaround the cooling drum with the stripes of adhesive to the outside.After passing A around the cooling drum, the coated web is then wound onthe storage roll I2.

The coated web produced by the above operation is illustrated in crosssection in Figure 2, wherein the web is indicated at 2 and thelongitudinal glue stripes are indicated by the reference numerals I3.

To form multiple layer stay tape, the procedure illustrateddiagrammatically in Figure 4 of the drawings is next carried out. In theembodiment illustrated stock rolls I2 and I2a of adhesively coated tapeforming material are provided, together with a roll Il-l of plain paperor the like, depending upon the nature of material being used. Thus,there is provided an upper web I5 having adhesive stripes I=6 on itslower surface, as can be seen in Figure 5, and a corresponding, lowerweb I5a having glue stripes |611` on its uppermost surface and facingthe web I5. Between the webs I5 and I5a is'the web I 'I which is theplain web. The three webs are led together between the heated rolls I8and I9 which serve to press together the webs I5, I'I and I 5a, the heatof the rolls reactivating the thermoplastic adhesive stripes IB and IBathereby causing them to adhere to opposite sides of the plain web I'I.

Following the joining of the webs I5, I5a and I'I, the combined webs arepassed around the cooling drum 20 which causes the thermoplasticadhesive to harden. After passing the cooling,V drum 2@ the combinedwebs may then be wound' on a storage roll 2|.

The multiple layer produce is seen in partial cross section in Figure 6,the section illustrating a width comprising four widths of tape. To obasa step in the continuous operation shown ink Figure 4, or it may be doneseparately. One of tain the individual widths of tape, the webs areV530the severed strips can be seen in Figures 7 and 8. It will be noted thatthe layers are adhered to each other along their longitudinal edges butthat intermediate these edges, i. e. the central or median area of thetape layers are free of each other. As seen in Figures 7 and 8, acoating of ordinary tape gumming 22 is applied to an outermost layer ofthe tape so that it may be adhered to a contacted surface. The coatingof tape gumming 22 may also be omitted centrally of the tape so that thelayer of tape material to which the gumming is applied will also be freeto flex intermediate its edges.

While we have described our invention in terms of a tape made up ofthree layers or plies of tape forming material, it will be understoodthat two, three, four or even more layers may be provided withoutdeparting from the principle and spirit of our invention. Where morethan two layers are employed, it is essential, however, that the gluestripes be in alignment with each other so as to maintain the properfree area centrally of the combined layers.

The adhesive employed to join the layers or webs of tape formingmaterial together is preierably a thermoplastic adhesive which can bereadily reactivated when the tape forming webs are combined. Of course,a Water activative adhesive may be used if so desired, but suchadhesives require application to the webs immediately prior to thejoinder of the webs, or else require the provision of means ahead of thecombining rolls to wet the adhesive.

The speciiic nature of the thermoplastic adhesive employed may be variedwidely and there are numerous substances known to the art which will besuitable to combine the layers. We prefer, however, to employ athermoplastic adhesive which is insoluble in water, such as wax, rosin,polyamide or polyvinyl acetate adhesives. Such adhesives have theability to resist being wetted by water and hence will not be affectedwhen the gummed tape, such as 22 in Figure 8, is moistened prior to theapplication of the tape to a carton being sealed.

In Figure 9 a section 23 oi the multiple layer tape is shown adheredover the meeting edges of walls 24 and 25 of the carton 25. Across-sectional view of the tape associated with the carton 26 is shownin Figure 10 greatly enlarged. It will be apparent from Figure 10 thatthe outermost layers of the tape are stretched about the corner whereasthe innermost layer is simply folded about the corner of the carton. Thetape layers, being unadhered to each other in the area along the edge ofthe carton, ex independently of each other and this has been found togreatly increase the shock resistance and ultimate strength of the tape.

The use of multiple tape layers, as noted, gives a decided increase inthe strength characteristics of a given weight oi tape forming material.By way of example of two sheets of kraft paper of 34 and 57 .5 lb. basisweights (24 x 36-500 sheets) gave individual Mullen or bursting strengthreadings of 35 and 58 lbs. per sq. in., respectively, for a total of 93lbs. per sq. in. Tested together in the form here disclosed, this twosheet combination resulted in a bursting value of per sq. in. Bycontrast a single sheet of kraft of identical type having a basis weightof 91.5 lbs. or equivalent to the combined basis weights of the 34 and57.5 lb. sheets gave a bursting strength of 83 lbs. per sq. in. Thus bythe combination we not only show an improvement over the sum of theindividual sheets but achieve an improvement in bursting strength ofapproximately over the single sheet.

As a second example, three sheets of kraft of 34.3, 50 and 53 lbs. basisweight show individual bursting strengths of 38, 47 and 60 lbs. per sq.in. for a total of 145 lbs. per sq. in. Tested together these samesheets show a bursting strength of 153 lbs. sq in. By contrast a singlesheet of kraft of identical type having a basis Weight of 142 lbs. oressentially equivalent to the compared basis Weights of 34.3, 50 and 581b. sheets gave a bursting strength of 109 lbs. per sq. in. Thus againby the combination We achieve an improvement in bursting strength thistime approximately 40% over the single sheet of es'- sentially equalWeight.

In Figures 1l and l2 We have shown an alternative construction in whichthe multiple layer tape is made from a single Width of tape-formingmaterial Which is folded and reversely folded to provide several layersof the finished tape. Referring to Figure 11, a sheet of tape-formingmaterial 2l, coated on one surface with a Water sensitive adhesive 28,is folded so as to provide the layers 23, 39 and 3| and the flapportions 32 and 33. In the illustrated embodiment, the adhesive 28 liesoutermost of the layer 3| and innermost of the layer 29. Thus theadhesive Will cover the outside portion of the flap 33 but the flapportion 32, Will, as to its external surface, be uncoated. However, byapplying Water as indicated at 34 and 35, and thereafter pressing thelayers 29, and 3| together, the flaps 32 and 33 will be adhered toadjacent portions of the layer 3l) and hence join the three layerstogether along their outermost edges, as illustrated in Figure 12. Theresult is again a product in which the individual layers are secured toeach other along their longitudinal edges and yet free to flexintermediate the edges.

Modifications may, of course, be made in our invention Without departingfrom the spirit of it, and we do not intend to be limited to the specieembodiments illustrated in any manner other than as expressed in theclaim which follows.

Having thus described our invention in certain exemplary embodiments,what We desire to secure by Letters Patent is:

A continuous strip of multiple layer stay tape for application to theedges of adjacent panels of box-board cartons to form joints, comprisinga plurality of plies of kraft paper of about 34 to about pounds basisWeight, said plies being of equal width and superposed one on the otherwith their adjacent longitudinal edges defining a common plane, marginaledge portions only of said plies being permanently securedl to eachother by laterally spaced stripes of adhesive extending lengthwise ofthe tape, the areas of said plies lying between said marginal edgeportions being free of adhesive and non-adhering and capable of beingflexed with respect to each other, said plies being disposed throughoutthe area thereof in substantially hat, juxtaposed face to face relation,whereby said tape may be continuously wound in a tight roll on an axistransverse to the length of the tape.

DONALD S. BRUCE'. PAUL W. HERRLINGER. HOWARD L. H'EISE.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 600,745 Sands Mar. l5, 1898 1,523,702 Moeller et al. Jan. 20,1925 1,707,515 Evans Apr. 2, 1929 2,142,463 Upson Jan. 3, 1939 2,237,346Gillillan Apr. 8, 1941 2,276,363 Zalkind Mar. 17, 1942 2,294,347 Baueret al Aug. 25, 1942 2,364,607 Dreher 'Dec. 12, 1944 2,501,815 Hamm Mar.28, 1950

